Regulation of Coordination of Molecular Motors

描述（由申请人提供）：细胞器和大分子复合物通过细胞质的运输对每个真核细胞都是必不可少的。这个过程是由马达蛋白完成的，马达蛋白利用ATP水解的化学能沿着微管和肌动蛋白丝移动它们的货物。运动依赖转运的时空控制对细胞分裂、细胞器运输和定位以及细胞内mRNA和蛋白质复合物的运动至关重要。细胞器运输和运动相关蛋白的缺陷促成或导致许多神经退行性疾病、神经纤维瘤病和色素沉着缺陷。本提案的目标是了解多个电机如何一起移动货物功能，以实现细胞中有针对性和及时的组件交付。我们想知道细胞中多个马达的活动是如何协调的以及这些马达是如何被调节的。两种生物模型将用于拟议的工作。来自非洲爪蟾的永久色素细胞（黑色素细胞）细胞系将用于研究运动调节。这是分析调控的理想系统，因为马达具有很好的特征，并且色素细胞器的运动可以由cAMP浓度的变化触发。培养的黑腹果蝇的神经元和吞噬细胞对RNAi敲除的蛋白质非常敏感，从而可以有效地分析与运动和运动协调有关的成分。本提案有四个具体目标：(i)寻找极性相反的微管电机之间的串扰机制；（ii）发现相同极性的多个电机是否能提高运输效率，并确定微管的运动在多大程度上有助于货物运输；（iii）发现肌凝蛋白马达如何沿着肌动蛋白丝和与货物相互作用的中间丝的网络移动，通过微管马达调节远程运输；（iv）寻找信号分子靶向货物细胞器的机制以及信号分子下游组分的身份。

DESCRIPTION (provided by applicant): Transport of organelles and macromolecular complexes through the cytoplasm is essential for every eukaryotic cell. This process is performed by motor proteins that use the chemical energy of ATP hydrolysis to move their cargo along microtubules and actin filaments. The spatial and temporal control of motor- dependent transport is critical for cell division, organelle transport and positioning, and the movement of mRNA and protein complexes within the cell. Defects in organelle transport and motor-associated proteins contribute or cause many neurodegenerative diseases, neurofibromatosis and defects of pigmentation. The goal of this proposal is to understand how multiple motors moving a cargo function together to achieve targeted and timely delivery of components in the cell. We want to know how the activity of multiple motors is coordinated in a cell and how these motors are regulated. Two biological models will be used for the proposed work. A permanent cell line of pigment cells (melanophores) from the frog Xenopus laevis will be used to study the regulation of movement. This is an ideal system for the analysis of regulation because the motors are well-characterized and movement of pigment organelles can be triggered by changes in cAMP concentration. Cultured neuronal and phagocytic cells from Drosophila melanogaster are extremely sensitive to protein knock-down by RNAi allowing for efficient functional analysis of components involved in motility and coordination of motors. This proposal has four specific aims: (i) to find the mechanisms of cross-talk between microtubule motors of the opposite polarity; (ii) to find if multiple motors of the same polarity make transport more efficient and determine to what extent movement of the microtubules contributes to cargo transport; (iii) to find how myosin motors, moving along a network of actin filaments, and intermediate filaments interacting with cargo, modulate long-range transport by microtubule motors; (iv) to find mechanisms of targeting signaling molecules to cargo organelles and the identity of components downstream of signaling molecules.